1. Field of the Invention
The present invention relate to an attachment with interchangeable jaws, and more particularly, to such an attachment in which jaws can be interchanged according to the work purpose in the use of the attachment attached to construction equipment such as an excavator and configured to crush or shear concrete or reinforcing bars.
2. Background of the Related Art
In general, for heavy construction equipment such as an excavator, a bucket for excavation, a crusher for crushing concrete and the like, and a shear for cutting reinforcing bars or iron plates are selectively used according to the work purpose thereof. In a place such as a site where a building is demolished, the frequent replacement between the crusher and the shear is very burdensome, and thus as disclosed in Korean Patent Registration No. 1004188640000 entitled “Processor of a Construction Apparatus for Destroying Concrete Structures and Cutting Steel Reinforcing Rods” of the applicant of the present invention, an attachment which can perform a crushing and shearing operation has been proposed. In addition, in many cases, such an attachment has a considerable weight and employs a quick coupler configured to be easily mounted on heavy construction equipment.
Meanwhile, the crusher and the shear have a common feature in that they are operated using jaws activated by a hydraulic cylinder. In addition, the crusher and the shear are distinguished from the bucket that does not include a separate mechanical link by itself. That is, the attachment can be used as a crusher when adopting jaws attached with spikes, and can be used as a shear when adopting jaws attached with blades.
Like this, for the sake of convenience of use, an attachment with interchangeable jaws are recently released, and an excavator demolition attachment with interchangeable jaw assemblies disclosed in U.S. Pat. No. 7,284,718 can be given as a representative example of the attachment.
FIGS. 1 to 4 are views for explaining the conventional prior art as described above, wherein FIG. 1 is a perspective view illustrating an outer appearance of an attachment, FIG. 2 are perspective views illustrating a main body unit and a jaw unit of the attachment, FIG. 3 is a conceptual view illustrating a process in which the jaw unit is engaged with the main body unit, and FIG. 4 is a perspective view illustrating the engagement relationship between the main body unit and the jaw unit.
As shown in FIG. 1 and, an attachment having interchangeable jaws includes a main body unit 100 joined to a front end of an arm of an excavator, and a jaw unit 200 mounted to the main body unit 100 and configured to be interchangeable. The main body unit 100 is provided with an operating cylinder 110 which is activated by being supplied with oil pressure from heavy construction equipment. In addition, the jaw unit 200 includes a pair of jaws, i.e., a lower jaw 210 and an upper jaw 220, which are pivotally interconnected with each other by a jaw pin 230. The attachment is used as a shear when the jaw unit whose each jaw may be attached with a blade 240 is mounted thereon, and may be used as a crushed when the jaw unit attached with or formed with spikes 250 is mounted thereon.
Further, the main body unit 100 includes a lock pin 120 that is moved in an extendable and retractable manner by oil pressure, and a hook pin-receiving portion 130 in the form of an open slot. The jaw unit 200 includes an insertion hole 260 so as to allow the lock pin 120 to be inserted thereto, and a hook pin 270 hooked in the hook pin-receiving portion 130.
In FIG. 3, there is shown a conceptual view illustrating a process in which the jaw unit 200 is engaged with the main body unit 100.
First, as shown in FIG. 3(a), the main body unit 100 is moved to approach the jaw unit 200, and the hook pin 270 is then insertedly hooked in the hook pin-receiving portion 130 (see FIG. 3(b)). Thereafter, the main body unit is pivotally rotated to align the centers of the lock pin 120 and the insertion hole 260 with each other, and then the lock pin 120 is extended into the insertion hole 260 to lock the jaw unit 200 to the main body unit 100 (see FIG. 3(c)). Then, when the operating cylinder 110 is connected to an operating cylinder connecting section 280 of the jaw unit 200, the interchange of the jaw unit is completed (see FIG. 3(d)).
FIG. 4 shows the operation of the lock pin for maintaining the engagement relationship between the main body unit and the jaw unit.
In the prior art, the lock pin is constructed in such a fashion that a lock pin cylinder 122 is moved in an extendable and retractable manner. That is, FIG. 4(a) shows a state in which the lock pin cylinder 122 is not inserted into the insertion hole 260 of the jaw unit 200, and FIG. 4(a) shows a state in which the lock pin cylinder 122 is moved to be inserted into the insertion hole 260 of the jaw unit 200.
However, the attachment according to the prior art as described above entails a problem in that since the lock pin 120 is provided only in a single number, it is frequently broken or damaged during the work. In addition, the conventional attachment encounters a drawback in that the lock pin 120 is fixed only at a central portion thereof to the main body unit, and thus the lock pin 120 is in a loosened state and is deviated from a normal position by vibration applied thereto during the movement of the heavy construction equipment, which makes it difficult to insert the lock pin into the insertion hole when the jaw unit 200 is locked to the main body unit 100.
Moreover, as shown in conceptual views of magnified circular portions indicated by a dotted line in FIG. 4, the lock pin 120 bears a work load while in use with it inserted into the main body unit 100 and the jaw unit 200. In this case, the lock pin cylinder 122 is deformed by the work load, so that an excessive load is exerted between the lock pin cylinder 122 and a lock pin piston 123, thereby resulting in deformation and abrasion of the lock pin. Furthermore, such a conventional attachment involves a shortcoming in that when eccentricity occurs upon the insertion of a front end of the lock pin cylinder 122 into the insertion hole 260, and thus a front end of the lock pin, i.e., the front end of the lock pin cylinder 122 in the prior art is deformed or damaged, the lock pin cylinder must be replaced in its entirety.